Method of encoding and decoding data signals

Abstract

In a multiple state data signal, a first and second state are equated to logic states while a third state is designated as a read state. The read state and one of the two logic states are alternately generated so that each logic state is immediately preceeded by a read signal which may be utilized to tell the peripheral that a valid bit of data follows.

What is claimed is: 
     
       1. In a radiopager code responsive system for interfacing with a peripheral device, a method of encoding a digital signal and decoding the encoded digital signal comprising the steps of: supplying a two level binary digital signal comprised of a series of data bits,   supplying a pulse signal with single pulses corresponding to each of said data bits,   combining the binary digital signal and the pulse signal to produce an encoded signal having a first level corresponding to one level of said two level binary signal, a second level corresponding to the other level of said two level binary signal and a third level immediately preceding each of said first and second level, for each of said data bite;   detecting when the encoded signal is at the third level and providing a decoded data output signal at one level at that time;   detecting when the encoded signal is at one of said first and second levels and providing the decoded data output signal at said one level at that time, and   detecting when the encoded data level signal is at the other of said first and second levels and providing the decoded data output signal at another level at that time, and   providing a pulse output signal with a single pulse occuring during each data bit of the decoded data output signal.